Post-Procedure Monocyte Count Levels Predict Major Adverse Cardiovascular Events (MACE) Following Transcatheter Aortic Valve Implantation (TAVI) for Aortic Stenosis

Background: Aortic stenosis has recently been characterised as having an inflammatory aetiology, beyond the traditional degenerative model. Recruitment of monocytes has been associated with inflammation contributing to progression of calcific aortic-valve disease. Prior research has demonstrated that pre-procedure inflammatory biomarkers do not consistently discriminate poorer outcomes in those with aortic stenosis. It remains, however, unclear if postprocedure inflammatory biomarkers, which are influenced by intraprocedural pro-inflammatory insults, can predict major adverse cardiovascular events (MACE) post transcatheter aortic valve implantation (TAVI). Method: All patients with postprocedure monocyte levels undergoing transcatheter aortic valve implantation at The Alfred Hospital, Melbourne, Australia (2008–2019) were included. The highest monocyte count from postprocedure days 1 to 3 was used. Patients were divided into “high” or “low” postprocedure monocyte count groups using the Youden Index. The incidence of 30-day MACE a composite of stroke, acute myocardial infarction, and death) was then compared. Results: In total, 472 patients were included (54% men, median age 84 years). Fourteen (14) patients (3%) suffered a 30-day MACE. Those with high postprocedure monocyte count were more likely to: be hypertensive (p=0.049); have a higher Society of Thoracic Surgeons risk score (p=0.032); and, undergo non-transfemoral access (p=0.018). A high (≥0.975) postprocedure monocyte count was significantly associated with 30-day MACE (odds ratio [OR] 1.16 for each 0.1 increase in monocyte, p=0.025). This association remained present on multivariable analysis adjusted for age, sex, Society of Thoracic Surgeons risk score, and self-expanding valve prosthesis type (OR 1.17, p=0.028). Conclusions: The association between postprocedure monocytosis and 30-day MACE suggests that minimising peri-procedural inflammatory insults may improve outcomes. This inexpensive and readily available biomarker may also aid in tailored risk stratification for patients.